A Spectrophotometric Method for the Identification of Lake Pigment Dyestuffs

Jo Kirby Technical Bulletin Volume 1, 1977

Abstract

This article is primarily concemed with the identification of red pigments by cutting thin sections of imbedded paint samples and plotting the spectral transmission curve in the visible part of the spectrum. Details are given of the imbedding procedure and the cutting of a section by a glass-knife microtome. The curves were plotted by means of a comparison microscope fitted with a variable interference filter and photomultiplier. Included is a brief outline of the chemistry of some of the main components found in various insect and plant red dyestuffs. The author presents a table of results for samples from a selection of paintings, at the end of the article.